Glacier studies in Northern Tien-Shan.

"Massive glaciers emerge from the side gorges. Visible from the valley, the firn fields of some of them hang on the mountain slopes like dazzling white cornices. Dark rocks and cliffs peek out from under the snow. Sometimes, a damp haze of cloud lingers in the gaps between them. The wild beauty of the surrounding landscape, still undeveloped by man, lingers in the memory."

"The Nature of Kazakhstan in Essays and Pictures." N.N. Palgov. 1950.

Central part of Zailiskiy Alatau range.

The Zailiskiy  Alatau is one of the outer ranges of the Tien-Shan, lying on the edge of the Kazakhstan plain, which extends northward. Eternal snow, rocks, and vegetation create a gamut of colors and shades. The central part of the ridge has an average altitude of up to 4,000 meters above sea level.
The highest peak, known as Talgar Peak, reaches 5017 meters. Numerous glaciers lie in the upper reaches of the ridge's gorges and valleys. There are up to two hundred of them, and this figure is not final. The area occupied by glaciers and snow reaches approximately 500 square kilometers.
Two-thirds of this area is located in the northern half of the ridge, and one-third in the southern half. The glaciers give rise to approximately two dozen mountain rivers, whose waters, during a single melting period, are capable of forming a lake approximately 12 kilometers in diameter and over 10 meters deep.
The largest glacial rivers of the Zailiskiy Alatau are the Chilik and Issyk. The waters of glacial rivers are not wasted. They are used to irrigate crops, for industrial use, to generate electricity, and, finally, for the daily needs of the numerous population.
Alma-Ata, the capital of the Kazakh SSR, relies exclusively on the water resources of two glacial rivers (Big and Small Almaty). Tens of thousands of hectares of collective farm fields stretch along the foothills of the mountains on either side of Alma-Ata, 70-100 km long, their flourishing appearance due to the melting of high-mountain snow and glaciers.
Just a dozen glacial rivers flowing into the northern foothills of the Zailiskiy Alatau can irrigate up to 20% of all irrigated land in Kazakhstan. Glaciers are the product of eternal snow. The more extensive and thick the eternal snow, the more significant the glaciers formed by it.
The study of the Zailiskiy Alatau glaciers began about 50 years ago. It became especially intensive and fruitful after the Great October Revolution. The All-Union Geographical Society, the Kazakh Hydrometeorological Service, and the Academy of Sciences of the Kazakh SSR participated in the study of the Zailiskiy glaciers.
It was personally initiated by glaciologist S.E. Dmitriev, continued by regional historian V.G. Gorbunov, and expanded by glaciologist N.N. Palgov. The most significant glaciation center in the ridge is located in the area surrounding its highest peak, Talgar Peak. Here, glaciation is concentrated in the headwaters of three rivers: the Chilik, Talgar, and Issyk. 
The largest glaciers are the Chilik Glaciers. The largest of these, named after the renowned geographer Korzhenevsky, stretches for almost 12 kilometers. The next largest glacier is the Bogatyr Glacier. It is located nearby in the same river basin.
At 8 kilometers long, it is distinguished by the areal size of its upper reaches. Both glaciers, quite similar to each other, represent a picturesque landscape, where thick snow, hanging like cornices on the mountain slopes, imparts a harsh yet magical appearance.
Both glaciers, one to two kilometers wide or more, like the Volga or Dnieper, meander majestically among rocky shores up to 700-1000 meters high. Their ends are buried in enormous banks of moraines they themselves have deposited, consisting of rocks, rubble, sand, and clay.
In the Talgar River basin, the largest glaciers, reaching 4-6 km in length, are: Dmitriev Glacier (named after one of the first and most prolific researchers of the Trans-Ili glaciers), Shokalsky Glacier (named after the luminary of Soviet geography, Yu. M. Shokalsky), Konstitutsii Glacier, Toguzak Glacier, and Kalesnik Glacier (named after the renowned geographer).
Dmitriev Glacier is distinguished by its considerable width in its upper reaches, reaching up to 5 km. Shokalsky Glacier is remarkable in that its canyon descends into the valley below all the ridge's glaciers, to an altitude of 3,270 m above sea level.
Furthermore, one of its branches has a picturesque and spectacular icefall. Konstitutsii and Toguzak Glaciers, lying adjacent to each other and formerly forming a single glacier, are the most typical valley glaciers of the ridge. Kolesnik Glacier turns.
The ridge is distinguished by its picturesque icefalls and steep, wall-like end, ending in a small moraine lake. In the Issyk River basin, the Academician Grigoryev Glacier stands out for its size, especially its width. At the source of the same river is the interesting Kassin Glacier (named after the famous geologist).
This glacier is characterized by the fact that the stream flowing from it exhibits a very close connection with it. On cold days, when the melting of the ice slows, the stream disappears. If the glacier's melting during the day was weak and short-lived, the stream sharply reflects this circumstance: it remains waterless for some part of the day.
The best-studied glaciers of the ridge are those located closer to the city of Almaty, lying at the source of the Small and Big Almaty Rivers: these are the Central Tuyuk-Su and Main Big Almaty Glaciers (also known as the Gorodetsky Glacier). Each of them is just over 5 km long.
The first faces north, the second west. Due to their different exposures, the end of the Central Tuyuk-Su Glacier lies at an altitude of 3,370 m. a. s. l., while the Main Bolshoi Almaty Glacier is at an altitude of 3,600 m. a. s. l. After many years of studying these glaciers, the main features of their life cycle have now become known, most importantly, their role in feeding rivers.
The life of glaciers is closely linked to climate. Climate can be used to judge the degree of glaciation in a country, and the extent of glaciation can be used to judge climate. Of the latter, the most important elements for glaciers are solid precipitation and summer air temperature.
The more snowfall in the glacier area and the cooler the summer, the greater the glacier's nutrition and the less loss from melting. Precipitation in the Zailiyskiy Alatau range is not particularly abundant. Most of it falls here in the spring and summer.
However, on glaciers, they rarely become liquid, and then only in the very lower reaches. Summer days are mostly cloudy, often overcast. The glaciers of the Zailiskiy Alatau move slowly, much slower than alpine glaciers. The highest observed velocity at one point on the Constitution Glacier was 17 cm per day.
At the ends of many glaciers, however, the velocity decreases to one centimeter per day or less. Sharp annual fluctuations in precipitation and summer air temperature greatly alter the position of the firn line - that is, the boundary between the snow-covered glacier surface and the snow-covered surface that remains covered year-round.
On the Central Tuyuk-Su Glacier, this line varied in height by more than 200 meters from 1937 to 1947. Overall, the area of ​​firn fields in the Zailiskiy Alatau has narrowed somewhat over the past few decades. This has caused the glaciers to become shorter and less active.
Their imperceptible rate of movement has become several times slower than it was 40-50 years ago. The Central Tuyuk-Su Glacier and the Main Big Almaty Glaciers can advance an average of 2 meters per year. However, in summer, their ends melt completely over a greater distance than they advance.
Consequently, these glaciers systematically retreat. The Main Big Almaty Glacier shrank from 76 to 123 meters in area between 1923 and 1946, representing 1.6% of its total area, including the firn fields. The Central Tuyuk-Su Glacier lost 2.3% of its area between 1937 and 1947.
In volume terms, this loss was 1.4 million cubic meters, converted into water. The more significant shrinkage of the Central Tuyuksu Glacier compared to the Main Big Almaty Glacier is due to its lower elevation above sea level and, consequently, higher summer temperatures.
While the average annual ice melt at the end of the Main Big Almaty Glacier is approximately 2 meters, the melted ice layer on the Central Tuyuksu Glacier reaches an average of 3 meters. Heavy snowfall in winter slows glacier shrinkage. It has been calculated that a 100 mm increase in precipitation results in a 43-meter lowering of the firn line on the Central Tuyuksu Glacier.
A 100-meter lowering of the firn line, in turn, increases the speed of the same glacier's movement by 1 meter the following year. And the faster a glacier moves, the more successfully it can fight for its survival. At a particularly significant rate of movement, the glacier will not only fail to shrink, but will actually begin to advance, meaning its end will move further and further forward each year.
For the Central Tuyuksu Glacier to increase its length, it would require, under the same climatic conditions, a speed six times greater than its current one. But the spatial state of the glacier is not only influenced by solid precipitation and the speed of movement.
It is equally, or even somewhat more, dependent on summer air temperatures. If the temperature drops by 1°C, the firn rainfall on the Tuyuksu Glacier decreases by 100 meters. For the Central Glacier to transition from the shrinking stage to the expansion stage, it would only require a 3°C decrease in summer air temperature.
In its own When combined, these two factors (precipitation and summer air temperature) exert a profound influence on the life of glaciers. When someone first sees glaciers with their firn fields dazzling in the sunlight, they are struck by the profound silence and stillness of their cold landscape.
Now we know that this silence conceals a tense struggle for life. Their stillness is only apparent. On warm summer days, the surface of the glaciers is covered with meltwater, which, gathering into streams, flows through icy canyons. On these days, on the plains, where everything dries under the hot sun, glacial rivers become more abundant and noisier.
The earth, cracked by the heat, greedily absorbs the revitalizing moisture of these rivers. A collective farmer gazes lovingly at the snow ridges from which the harvest of his crops is saved. Glaciers play a significant role in replenishing rivers in summer.
The main Big Almaty and Central Tuyuksu glaciers provide up to 30% of the total runoff of the rivers they feed during the summer, due to melting ice. If we include the melting of firn fields, the glaciers' contribution reaches 40%. The observed shrinkage of these glaciers, and all others in the Zailiysky Alatau, has very little effect on the water content of the rivers they feed - so little that it is undetectable by hydrometric measurements.
The stage of glacier shrinkage, barring special conditions, is not infinite. Even if the current unfavorable climate persists, it may sooner or later transition to a stage of glacier growth. A 20-cm-thick layer of snow, equivalent to water, accumulates year after year on the firn fields of the Central Tuyuksu Glacier and its tributaries.
This gradual accumulation, which increases pressure in the cirque region (the head basin of the glacier), will ultimately cause a sharp acceleration in the movement of the ice masses. As a result, the supply of ice at the glacier's terminus will increase to such an extent that it will more than cover the melting loss.
The increase in the area of ​​the glacier masses will have a positive impact on the water resources they produce.

Authority:
"The Nature of Kazakhstan in Essays and Pictures." N.N. Palgov. Publishing House of the Academy of Sciences of the Kazakh SSR. Alma-Ata. 1950.